Solar sensor including reflective element to transform the angular response

ABSTRACT

A solar sensor that utilizes a blocking element and curved reflective element between the sun and a photo-sensitive electronic device to provide high signal levels and the ability to shape the angular response of the overall sensor. A particular angular response can be achieved by combining the attenuating affects of the blocking element with the increased response affects of the curved reflector. These two elements may be combined into one physical structure, or may be separate. Further, the present invention contemplates the use of multiple blocking elements and multiple reflectors.

[0001] This application claims the benefit of priority to U.S.provisional application 60/466,815, filed Apr. 30, 2003, which isincorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to solar sensors for that respondto the position of the sun, and in particular solar sensors used foradjustment of climate controls of a vehicle.

BACKGROUND OF THE INVENTION

[0003] Generally, photodiodes have a cosine angular response, meaningthat the peak response of the photodiode is achieved at a normal angleof incidence where light is impinging perpendicular to the surface. Thisresponse gradually decreases according to the cosine function to a zerooutput at 90°.

[0004] This cosine response is a drawback in some types of solarsensors. In some vehicles, a solar sensor is used to measure solarheating by sunlight. The sensor represents a sampling of the heatingaffect occurring on some object, such as a vehicle. However, the solarheating affect only follows the cosine response for objects that areflat. Thus, the use of photodiodes is sometimes limited to modeling theheating of flat objects.

[0005] However, many practical solar sensor applications, includingespecially those with a passenger compartment of a vehicle, are helpedby sensors whose response corresponds to such complex three-dimensionalshapes.

[0006] One of the design goals of automotive solar sensors is to respondto sunlight in a fashion that is consistent with the heating affects onthe passenger compartment. In general terms, the desired overheadresponse is about 50% of the peak response, due to the shading effectsof the roof. The peak response typically occurs at about 50° fromoverhead. The response at the horizon is generally desired to be about50 to 70% of the peak response, due to the relatively large area ofglass exposed in that angular region.

[0007] Some automotive solar sensors use a domed diffuser to provideincreased response when the sun is near the horizon. The thicker topsection reduces the overhead response inherent in the photodiode'scosine-related angular response. One difficulty with this approach isthe significant reduction in overall signal current due to the loss oflight through the diffuser material. In some solar sensors, the use of adiffuser provides lower signal output for a given size diode, requires alarger diode to achieve a given signal output level, may requireadditional signal amplification for proper signal processing, and may becharacterized with a decreased signal to noise ratio due to theattenuated signal.

[0008] What is needed are apparatus and methods which overcome theproblems in other solar sensors. The present invention does this in anovel and unobvious manner.

SUMMARY OF THE INVENTION

[0009] One embodiment of the present invention is a unique method toadjust the response characteristics of a solar sensor by combining bothsolar radiation blocking features and solar radiation reflectingfeatures. Other embodiments include unique apparatus and systems formodifying the response characteristics of a solar sensor.

[0010] A further embodiment of the present invention pertains to anapparatus whose output corresponds to the angular position of a sourceof radiation, such as the sun. For some angular positions of the source,one or more opaque regions or opaque bodies block a portion of theradiation from falling incident upon a photosensitive electronic device.In yet other positions of the radiation source, a portion of theradiation that would otherwise have missed the photosensitive electronicdevice is instead reflected onto the device.

[0011] In yet other embodiments of the present invention, an apparatusfor responding to the angular position of a radiation source includesone or more reflective surfaces. Preferably the reflective surfaces arecurved. The curved shapes can be spherical, parabolic, and conical. Someembodiments of the present invention do not include blocking elements.

[0012] Further objects, embodiments, forms, benefits, aspects, features,and advantages of the present invention can be obtained from thedescription, drawings, and claims provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a schematic representation according to one embodimentof the present invention.

[0014]FIG. 2 is a schematic representation of the embodiment of FIG. 1,with the sun shown in a different location.

[0015]FIG. 3 is a schematic representation of the embodiment of FIG. 1,with the sun shown in a different location.

[0016]FIG. 4 is a schematic representation of the embodiment of FIG. 1,with the sun shown in a different location.

[0017]FIG. 5 is a schematic representation of the embodiment of FIG. 1,with the sun shown in a different location.

[0018]FIG. 6 is a schematic representation of the embodiment of FIG. 1,with the sun shown in a different location.

[0019]FIG. 7 is a schematic representation of a vehicle climate controlsystem according to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] While the present invention may be embodied in many differentforms for the purpose of promoting an understanding of the principles ofthe invention, reference will now be made to the embodiments illustratedin the drawings and specific language will be used to describe the same.It will nevertheless be understood that no limitation of the scope ofthe invention is thereby intended. Any alterations and furthermodifications in the described embodiments, and any further applicationsof the principles of the invention as described herein are contemplatedas would normally occur to one skilled in the art to which the inventionrelates.

[0021] This application incorporates by reference the following U.S.patent applications: Ser. No. 220,021, filed Jul. 15, 1988, which issuedas U.S. Pat. No. 4,933,550; Ser. No. 08/653,818, filed May 28, 1996,which issued as U.S. Pat. No. 5,670,774; Ser. No. 09/188,824, filed Nov.9, 1998, which issued as U.S. Pat. No. 6,084,228; Ser. No. 09/554,297,filed May 11, 2000, which issued as U.S. Pat. No. 6,297,740; Ser. No.09/269,701, filed May 31, 1999, which issued as U.S. Pat. No. 6,243,002;and Ser. No. 09/508,789, filed Mar. 16, 2000, which issued as U.S. Pat.No. 6,396,040.

[0022] The present invention relates to a solar sensor which provides asignal that corresponds to the angular position and intensity of asource of radiation, such as the sun. In one embodiment, the sensor ispart of a system for controlling the climate within a vehicle.

[0023] Previous systems for controlling the climate within a vehicletended to use sensors with limited responses. The sensor would provide asignal output that corresponded to the relative placement between thesensor and the sun, such as along fore and aft, and right and leftdirections. The output of the sensor would change in a mannercorresponding to the radiation from the sun striking a two-dimensionalplatform.

[0024] Other solar sensors lack the methods and structures for modelingthe vertical attributes of the passenger compartment of a vehicle. Forexample, the roof of a vehicle is spaced several feet above the fronthood or trunk compartment body sections. Therefore, when the sun isrelatively close to the horizon, the front, side, and rear glass of thevehicle compartment allow significant amounts of solar radiation toenter the vehicle compartment. If a solar sensor improperly models thevehicle compartment, this heating affect at low solar angles is notapproximated.

[0025] In contrast, a solar sensor according to one embodiment of thepresent invention includes a reflective surface and provides a betterapproximation of the vehicle compartment. The shape of this reflectivesurface is adapted and configured such that when the sun is at lowangles above the horizon, radiation from the sun which would otherwisenot fall incident on the photo-sensitive electronic device is insteadreflected off of the reflecting surface and onto the active surface ofthe photo-sensitive electronic device. In some embodiments, the solarsensor does not include a diffuser. By not including a diffuser, theseembodiments provide higher signal levels for a given size photodiode. Inother embodiments, a smaller photodiode can be used to achieve a givenoutput signal, thus reducing the sensor cost. Further, subsequent signalamplification can be reduced owing to the increased photocurrent levels.Because the signal levels are higher, the signal to noise ratio isimproved.

[0026] In one embodiment of the present invention, an approach isdeveloped that uses a shaped blocking element and a curved reflector totransform the inherent cosine angular response of a photodiode into aresponse more representative of a three-dimensional vehicle compartment.In some embodiments of the present invention, the output response of thephotodiode is changed for some angular ranges of the incoming solarradiation relative to the normal cosine response. For other angularranges of solar radiation the response is decreased relative to thenormal cosine response.

[0027] In one embodiment of the present invention, the response of thesensor to overhead radiation is attenuated by placing a substantiallyopaque portion of a body above the photosensitive electronic device. Yetother embodiments of the present invention include a sensor withincreased response when the solar radiation approaches the sensor fromangles closer to the horizon. In such embodiments, a reflecting elementis placed above the photosensitive electronic device such that incominglight is reflected off of the reflecting surface and onto the active,planar surface of the electronic device.

[0028] In some embodiments, the reflecting surface is generally abovethe electronic device. In yet other embodiments, the electronic deviceis in-between the source of radiation and the reflecting element, suchas the case where the reflecting surface is located aft of theelectronic device. Solar radiation entering the sensor housing at nearhorizontal angles passes over the electronic device, strikes thereflecting surface aft of the device, and is reflected forward anddownward onto the active surface of the electronic device. In yet otherembodiments, the detector is placed over the reflector, with thedetector thus functioning as a blocking element. In yet otherembodiments, the detector is placed to the side of the reflector or offto the side, at a downward-facing angle.

[0029]FIG. 1 is a schematic representation of an apparatus 20 accordingto one embodiment of the present invention. Apparatus 20 includes ahousing 30 having a photosensitive electronic device 22 located therein.Electronic device 22 can be of any type which modifies and/or producesan electrical signal in response to the incidence of solar radiation onan active element. As one example, device 22 can be a single photodiodeor an array of photodiodes. In some embodiments using multiplephotodiodes, there is also an opaque divider which minimizes the“cross-over” effects as the angle of the sun changes. The figures ofthis application are not drawn to scale. As one example, the thicknessof housing 30 is not representative.

[0030] As another example, electronic device 22 can be a singlephotocell or an array of photocells. In some embodiments of the presentinvention, the electronic device 22 includes one or more active elementsarranged on a generally flat, planar surface. However, the invention isnot so limited, and contemplates nonplanar arrangements ofphotosensitive electronic devices.

[0031] Although the term “solar radiation” is used herein, variousembodiments of the present invention pertain to sensors which can sensethe orientation of a radiation source other than the sun. Further, it isunderstood that the photosensitive electronic device of the presentinvention can be sensitive to one or more portions of the spectrum ofsolar radiation, and may not be sensitive to some portions of the solarradiation spectrum at all. The sensor's overall spectral response is thecombination of the spectral response of the photosensitive electronicdevice and the spectral transmission of the housing. Two examples ofspectral responses are “eye-like response” and “near-infrared response.”In some embodiments, the housing is tinted to provide a predeterminedspectral response.

[0032] Housing 30 of apparatus 20 is preferably a dome-shaped, generallytransparent cover for protection of electronic device 22. In otherembodiments, housing 30 is flat or has a complex curved profile. In someembodiments, housing 30 can include cosmetic texturing to provide somescattering or reorientation of solar energy that is incident upon outersurface 32 as it travels through the thickness of the housing wall andexits interior surface 34. However, the invention is not so limited, andhousing 30 can have little, if any, diffusive properties. In a preferredembodiment, housing 30 does not have any diffusive properties. Housing30 as shown in FIGS. 1-7 is depicted schematically, and not to scale.

[0033] Housing 30 preferably includes a blocking and reflecting elementsuch as a body 40 which depends downwardly from interior surface 34toward electronic device 22. In other embodiments, the blocking andreflecting element is accomplished as a coating applied housing 30. Inone embodiment body 40 is generally hemispherical and includes areflecting surface 42 on a convex portion of the body. Further, body 40preferably includes a surface which is at least partly opaque. Referringto FIG. 1, the opaque portion of body 40 can be a generally opaquecoating 44 along the convex surface of body 40. Further, the blockingelement could be a generally opaque coating along the interface 46between body 40 and interior surface 34. For a source 10 of solarradiation as shown in FIG. 1, either opaque coating 44 or opaque coating46 constitutes a shadow element projecting a shadow 50 onto the surfaceof electronic device 22.

[0034] Although what has been shown and described is an opaque portionof body 40 which casts shadow 50 onto device 22, the present inventionis not so limited. The opaque portion of apparatus 20 can be a portionof housing 30, including portions on the outer surface 32 or innersurface 34, or embedded within the wall of housing 30. Further, theopaque portion of apparatus can be of a different size and/or shape thanbody 40. For example, as seen in FIG. 1, body 40 is generallyhemispherical. However, an opaque portion of housing 30 could berectangular in shape.

[0035] The size of the projected area of the blocking element helpsdetermine the response of electronic device 22 to an overhead radiationsource. For example, a blocking element that is relatively smallprovides a relatively large response from electronic device 22 to asource 10 that is located above both the blocking element and theelectronic device.

[0036]FIG. 1 shows the source 10 of solar radiation to be generallyoverhead of apparatus 20. Because of the opacity of body 40, a shadow 50is cast generally onto the center of the active planar area ofelectronic device 22. There is little or no reflection of radiation fromsource 10 on the reflective surface 42 of body 40.

[0037] Referring to FIG. 2, the source 10 of solar radiation isdisplaced a moderate angle from the overhead position. Radiation fromsource 10 cannot penetrate the opaque portion 46 of body 40, and ashadow 50 is cast toward an edge of device 22. A portion of shadow 50obscures some of the active area of device 22. However, the remainder ofshadow 50 is cast on non-active portions of apparatus 20, which has noaffect on the output of 22. Depending upon the shape of body 40, therecan be little, if any, light reflected from surface 42 onto device 22.

[0038]FIG. 3 is a schematic representation in which radiation source 10is near the-horizon. Radiation from source 10 is generally parallel tothe active surface of device 22. However, some of the radiation passesthrough housing 30 and falls incident upon the reflective surface 42 ofbody 40. Because of the convex shape of surface 42, this solar radiationis reflected off of surface 42 and falls incident upon the photoactiveelements of device 22, thus causing the response of device 22 to change.

[0039] In yet other embodiments of the present invention, a reflectivecoating 48 can be placed along an interior wall 34 of housing 30.Radiation from source 10 would pass over device 22, and reflect forwardoff of reflective surface 48 onto device 22. In some embodiments, thepresence of reflecting surface 48 may be at least partly opaque forradiation received from the rear of apparatus 20. However, this may beacceptable in those embodiments in which apparatus approximates avehicular compartment with a relatively small rear window.

[0040]FIGS. 1, 4 and 5 illustrate schematically the range of angles overwhich the opaque portion of apparatus 20 influences the output ofelectronic device 22. Referring to FIG. 1, when source 10 is generallyoverhead of apparatus 20, a shadow 50 is cast directly downwards frombody 40. As radiation source 10 moves to the angle represented in FIG.4, a generally elliptical shadow 50 is cast by body 40 onto device 22.One edge of the elliptical shadow intercepts an edge of the photoactivearea of device 22. For a source of radiation shown in FIGS. 1 and 4, theopaque portion of apparatus 20 has maximum and near-maximum affect ondevice 22. However, as source 10 further inclines toward the horizon(referring to FIG. 5) the elliptical shadow area 50 completely falls outof the active area of device 22. For the angle depicted schematically inFIG. 5, the opaque blocking features of apparatus 20 no longer affectthe output of device 22.

[0041] Referring to FIG. 6, source 10 is shown at an angle at whichradiation from the source begins reflecting off of surface 42 and ontothe active area of device 22. From this angle, and continuing for anglesto the horizon, the reflecting surface 42 reflects radiation from source10 onto the active area of device 22 and thereby modifies the output ofdevice 22.

[0042] In one embodiment of the present invention, the range of anglesfrom the overhead position (FIG. 1) to the position shown in FIG. 5,comprise a first range of angles over which the opaque portion of thebody modifies the output of device 22. There is a second range of anglesfrom the angle shown in FIG. 6 to the angle shown in FIG. 3 over whichradiation from the source is reflected off of reflecting surface 42 andonto the active area of device 22. Both the first range of angles andthe second range of angles are less than the total range of angles overwhich device 22 is responsive to solar radiation.

[0043] In some embodiments of the present invention, the first andsecond angular ranges overlap. That is, there are certain angularpositions of the source of radiation for which there is a shadow cast onthe electronic device, and also a portion of the radiation is reflectedonto the electronic device. In yet other embodiments of the presentinvention, the first and second angular ranges are mutually exclusive.That is, the shadow cast by the opaque portion of the body falls off ofthe active area of the electronic device before any radiation isreflected off of the reflecting surface and onto the active area of theelectronic device. Whether the first and second angular ranges areoverlapping or exclusive can be chosen by selecting the size, shape andlocation of the opaque portion of apparatus 20 and the size, shape andlocation of the reflecting portion of apparatus 20.

[0044] Although what has been shown and described is an apparatusincluding a body 20 that provides both blocking and reflection ofincident radiation, the present invention is not so limited. Blocking ofincident radiation can be created by one or more coatings or localizedsurface treatments on housing 30. Likewise, reflection of radiation ontothe electronic device can be accomplished by one or more reflectivecoatings and/or reflective bodies attached to apparatus 20.

[0045]FIG. 7 is a schematic representation of a solar sensor accordingto one embodiment of the present invention as used within a vehicularsystem. System 100 includes a solar sensor 20. Radiation from a source10 falls incident upon a photosensitive electronic device. This incidentsolar radiation changes the output characteristics of device 22, and asignal 110 corresponding to the incident solar radiation is received byan electronic controller 120. The electronic controller 120, which maybe digital or analog, receives a variety of sensor and control inputs.In response to these various inputs, controller 120 establishes one ormore output control signals 130 to various actuators (not shown) of aclimate control system within a passenger compartment 140 of a vehicle150. For example, controller 120 can control whether or not the airconditioning compressor is turned on, or the amount of heat from theengine being provided to a heat exchanger. In yet other embodiments ofthe present invention, controller 120 also controls the state of theheadlights 160 of vehicle 150.

[0046] While the invention has been illustrated and described in detailin the drawings and foregoing description, the same is to be consideredas illustrative and not restrictive in character, it being understoodthat only the preferred embodiment has been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected. It should be understood thatwhile the use of the word preferable, preferably or preferred in thedescription above indicates that the feature so described may be moredesirable, it nonetheless may not be necessary and embodiments lackingthe same may be contemplated as within the scope of the invention, thatscope being defined by the claims that follow.

What is claimed is:
 1. An apparatus comprising: a photo-sensitiveelectronic device having an active surface for collection of incidentsolar radiation; a generally transparent housing located over saidelectronic device, said housing including a shadow element located abovethe active surface and projecting a shadow onto the active surface; anda reflective surface located between the active surface and the shadowelement and reflecting light onto the active surface.
 2. The apparatusof claim 1 wherein the output characteristics of said electronic deviceare modified because of blocking of solar radiation from the planarsurface by said shadow element and reflecting of solar radiation fromsaid reflective surface onto the active surface.
 3. The apparatus ofclaim 1 wherein said electronic device is a photodiode.
 4. The apparatusof claim 1 wherein said shadow element is substantially opaque.
 5. Theapparatus of claim 1 wherein said shadow element is partly opaque. 6.The apparatus of claim 1 wherein said housing is dome-shaped anddiffuses solar radiation incident thereon.
 7. The apparatus of claim 1wherein the active surface has a first area, the projected shadow has asecond area, and the second area is less than the first area.
 8. Anapparatus for collecting solar radiation, comprising: a photo-sensitiveelectronic device having a planar surface for collection of incidentsolar radiation; a body located above the planar surface, said bodyhaving a substantially opaque portion, said body having a reflectingsurface; wherein the solar radiation is incident upon the planar surfaceover a first range of angles, a portion of the solar radiation isblocked from the planar surface by the opaque portion over a secondrange of angles, and a portion of the solar radiation is reflected ontothe planar surface by the reflecting surface over a third ranges ofangles, the first range is greater than either the second range or thethird range, and the second range is different than the third range. 9.The apparatus of claim 8 wherein the second range includes solarradiation that is substantially normal to the planar surface.
 10. Theapparatus of claim 8 wherein the third range includes solar radiationthat is substantially parallel to the planar surface.
 11. The apparatusof claim 8 wherein the shape of the reflecting surface is chosen fromthe group including partially spherical, parabolic, conical, orfrusto-conical.
 12. The apparatus of claim 8 effect of blocking elementand reflecting element exclusive or overlapping.
 13. The apparatus ofclaim 8 wherein the second range and the third range are overlapping.14. The apparatus of claim 8 wherein the second range and the thirdrange are mutually exclusive.
 15. The apparatus of claim 8 which furthercomprises a dome-shaped housing, said photo-sensitive electronic devicebeing contained within said housing, said body being attached to saidhousing.
 16. An apparatus for collecting solar radiation, comprising: ahousing including a portion which transmits solar radiation incidentthereon, said housing having an interior surface, said housing includingan opaque portion; a photo-sensitive electronic device located withinsaid housing and having a photo-responsive surface which receives solarradiation and modifies an electrical signal in response thereto; and abody located on the interior surface of said housing, said bodydepending from the interior surface toward the photo-responsive surface,said body having a reflecting surface; wherein the solar radiation isincident upon the photo-responsive surface over a first range of angles,a portion of the solar radiation is blocked from the photo-responsivesurface by the opaque portion over a second range of angles, and aportion of the solar radiation is reflected onto the photo-responsivesurface by the reflecting surface over a third ranges of angles, thefirst range is greater than either the second range or the third range,and the second range is different than the third range.
 17. Theapparatus of claim 16 wherein the reflecting surface is generallycentered above the photo-responsive surface.
 18. The apparatus of claim16 wherein the reflecting surface is not generally centered above thephoto-responsive surface.
 19. A method for adjusting the climatecontrols of a vehicle, comprising: providing a sensor in a housing fordetecting solar radiation incident upon a vehicle and a controller foradjusting the climate controls of the vehicle in response to a signalfrom the sensor, the housing including a substantially reflectingsurface; receiving solar radiation upon the housing, a portion of thesolar radiation being transmitted at an angle such that the portion doesnot fall directly incident upon the sensor; reflecting the portion offof the reflecting surface and onto the sensor; modifying the output ofthe sensor in response to the reflected portion; providing the sensoroutput to the controller; and adjusting the climate controls of thevehicle.
 20. The method of claim 19 which further comprises receiving asecond portion of the solar radiation upon the housing transmitted at asecond angle, the second angle intercepting the sensor, and preventingthe second portion from falling incident upon the sensor.